1. Field of the Invention
The present invention relates to a dry type developer utilized in an image recording apparatus such as a copy machine, a printer, and particularly to a dry type developer utilized in an image recording apparatus in which an aperture electrode with a plurality of apertures is installed and an image is directly recorded on a recording medium by controlling whether the dry type developer is passed through each of the apertures or not, based on an image information of the image to be recorded on the recording medium.
2. Description of Related Art
Conventionally, as image recording methods, an electrophotographic method and an electrostatic recording method are generally used in an image recording apparatus such as a copy machine, a printer, etc.. And various dry type developers (toner) are used in a field of these recording methods.
Here, in the electrophotographic method using the dry type developer, a latent image is electrostatically formed on a photosensitive member composed of photoconductive material and the latent image is developed into a visible image by the dry type developer. Thereafter, the visible image itself is fixed on a recording medium by heating and pressing thereof.
The toner used in such recording method is classified into two types of the toners; one type belongs to the one component system in which the image is developed by only coloring particles including a resin component and a pigment, and the other type belongs to the two components system in which the image is developed by particles such as ferrite, glass bead and the coloring particles used in the above one component system.
The image recording apparatus utilizing the electrophotographic method or the electrostatic recording method is very complex and there is a limit in high resolution of the image if using the toner produced by a comminution method. Because, when the image is recorded on the recording medium so as to reproduce fine lines by using the atomized toner, the minimum particle size (particle diameter) of the toner produced by the comminution method is about 7 .mu.m at best and further it is almost impossible to obtain more finer toners than 7 .mu.m so long as using the comminution method.
On the other hand, a method for producing the toner by polimerization without using the comminution method is proposed. For example, such method is disclosed in Japanese Patent Application Laid Open No.s 57-102,666, 63-304,002. Though, by using such disclosed method, it can be produced the toner particles finer than 7 .mu.m by polimerization and thereby be realized the high resolution of the image, the polimerized toner articles are tend to adhere to the photosensitive member composed of the photoconductive material in the electrophotographic apparatus, as a result, cleaning of the photosensitive member cannot be effectively conducted because the adhered toner articles are not easily taken away from the photosensitive member, if the polimerized toner articles are utilized in a developing process of the electrophotographic apparatus.
Therefore, methods in which the image is recorded on the recording medium without using the photosensitive member are variously proposed, and in such proposed methods, the method disclosed in U.S. Pat. No. 3,689,935 is well-known. In such method, an image recording apparatus having a control means which comprises an aperture electrode, the aperture electrode being constructed by forming a plurality of apertures in a straight line through an electrode plate including two electrodes formed on opposite sides of an insulating layer, is utilized. And the image is recorded on the recording medium arranged opposite to the aperture electrode by controlling whether the toner provided from a toner providing device is passed through each of the apertures.
However, in the image recording apparatus disclosed in U.S. Pat. No. 3,689,935, quality of the recorded image is extremely affected by particle size distribution of the toner. Here, in order to appreciate the particle size distribution, a ratio both the average particle size calculated based on particle volume (abbreviated APSV hereinafter) and the average particle size calculated based on particle number (abbreviated APSN hereinafter) is generally calculated. And if the ratio of APSV and APSN is bigger than a predetermined value, the particle size of the toner is ununiformly distributed and thereby, the toner cannot be uniformly charged. On the other hand, if the ratio of APSV and APSN is smaller than a predetermined value the particle size of the toner is uniformly distributed and thereby, the toner can be uniformly charged.
Therefore, in case that the toner having the ratio of APSV and APSN, which is bigger than the predetermined value, is used in the image recording apparatus mentioned above, concentration of the toner passing through the apertures in the aperture electrode is made ununiform and thus, the image is ununiformly recorded on the recording medium. Further, there are problems that the toner is passed through the apertures in the aperture electrode, through which the toner must not pass and that the apertures are blinded by the toner because the toner is charged ununiformly.